Apparatus for making blanks and strips of blanks

ABSTRACT

Polygonally-shaped blanks useful in making products such as can parts are formed by dividing a relatively wide web of material into a plurality of relatively narrow strips, each strip having longitudinal edges delimited by scroll lines formed from a plurality of straight scroll line sections. The strips can be arranged parallel to a longitudinal axis of the web or at an angle relative thereto. It is also possible to divide the strips into individual blanks at a scrolling station or at a remote can making station. The polygonal shape of the blanks permits them to be designed so as to compensate for earing caused by the anisotropy of the material from which the web is made. Various punches and slitting arrangements can be employed to perforate the web and to longitudinally and laterally cut it so as to form the strip and/or blanks therefrom.

This is a division of application Ser. No. 751,040, filed July 1, 1985,now U.S. Pat. No. 4,681,001.

FIELD OF THE INVENTION

The present invention relates to the formation of blanks or strips ofblanks, and, more particularly, to methods and apparatus for slitting,cutting and perforating a web of material to form such blanks or strips.

BACKGROUND OF THE INVENTION

In the conversion processes of sheet or coiled metals and nonmetals,including laminations, the area usage efficiency of the material is ofprimary importance and essential for economic and competitiveoperations. The economic aspects are of special relevance, particularlyin the packaging industry which depends almost entirely on massiveoutput quantities, wherein the efficiency of material usage has beenrecognized for many years as being very important, especially whenindividual blanks from which a given component is made are round orcircular in shape.

If the conversion equipment contains only one blanking tool, thematerial utilization efficiency factor could be π/4 at best, when noshred allowance in the remaining skeleton is contemplated. Hence, inpractice, the optimum material utilization factor would be around 75percent, while leaving a manageable skeleton in the rectangular stripsor straight-sided webs.

In the case of multi-tool equipment, wherein two or more blanks aresimultaneously stamped, it is possible to employ a 60° staggeredpattern, which improves the material utilization factor to a figure ofaround 85 percent depending on the shred width in the remaining skeletonand the number of blanks accommodated across the width of the web. Sucha figure is usually achieved when non-coated stock is employed, but canalso be achieved when high volume justifies coil coating.

Over the past thirty years, can making industries started so-calledprimary scrolling of coiled materials to thereby produce sheets withscrolled leading and trailing edges. Such sheets could then be coatedand secondarily scrolled, before being converted into components, toform single row, double row, or even multiple row strips. This practiceresults in a material utilization factor of about 85 percent dependingon the shred width in the remaining skeleton.

In most applications of present can making practice, circular blanks areused for the manufacture of can end components or for providing "cups"suitable for so-called "two-piece cans", wherein the circular base andcylindrical wall are Joined without any seams. The material for thetwo-piece cans may be of a ferrous or non-ferrous character.

Usually the rolling mills finish the coils specified for deep drawing insuch a way that so-called "earing" caused by the cupping operation is ata minimum. Earing is due to the anisotropy of the grain structure in thematerials, the typical number of ears in ferrous materials being six.For circular blanks, earing results in the use of a larger diameterblank in order to provide an acceptably high cup. To avoid the use oflarger diameter blanks, non-circular blanks could be used, such blanksproviding additional material from the skeleton shred in the localitiesbetween the anticipated ears in the cup. However, blanking dies for suchblanks are not practicable.

The established practice anticipates efficient utilization of widecoiled material using multi-die cuppers, which is practicable for highoutputs only. To keep high utilization of material in case of lowproduction outputs, wherein a single blanking or cupping tool isapplicable, the coiled material needs to be processed twice, namely atfirst to cut the web into sheets, i.e., primary scrolling, and thensecondly to cut the sheets into strips by secondary scrolling. Thismeans more handling through costly additional equipment. Hence, singletool, low output mini-lines cannot compete successfully with the highspeed multi-die production lines.

SUMMARY OF THE INVENTION

The present invention has numerous objects in view of the problems andshortcomings of the prior art described above. For instance, one objectis to provide a method and apparatus for longitudinally scroll slittinga wide web of coiled material to provide narrow strips containing one,two or three rows of blanks, the strips being suitable for blanking orcupping by an appropriate tool arrangement. The strips are designed soas to minimize the shred generated by cutting out individual blanks,thus offering economic material area utilization.

Another object of the present invention is to provide a method andapparatus for longitudinally scroll slitting a wide web of coiledmaterial, as aforesaid, wherein slitting is combined with punching oftriangular holes in the web in a specific relationship relative to thelongitudinal scrolled edges, thereby creating a strip containing asingle row of blanks. By cropping the strip along discrete lines,twelve-sided blanks are produced. These blanks, which are especiallyadapted for cupping, produce no shred during the cupping operation and,thus, substantially increase the efficiency of material utilization.

A further object of the invention is to arrange the twelve-sided blankconfiguration, produced as aforesaid, in such a way that the effect ofanisotropy in the form of ears and valleys between the ears in the drawncups can be compensated for by adding extra material in the localitiesbetween the potential ears. By taking such extra material from an areaof the web which would normally be disposed of as scrap, the materialutilization factor can be increased above that for circular blankswithout shred allowance in case of homogeneous isotropic materials.

Yet another object of the invention is to extend the use of thetwelve-sided blanks, produced as aforesaid, to strips containing morethan one row of blanks and up to full width webs, wherein punching toolsare provided in front of the cupping dies. The cupping dies are providedwith cropping tools such that no shred skeleton is left after thecupping operation.

A still further object of the present invention is to provide a methodand apparatus for simultaneously scroll slitting and cutting the webwith punched triangular-shaped holes by using a combination of scrollslitting knives and flying scroll dies. Double scrolled strips thusobtained are suitable for circular blanking and may also be used formaking twelve-sided blanks, because the wide web has been pre-punchedwith triangular-shaped holes. The slitting knives and the flying dieswill produce twelve-sided blanks in one operation, thus saving handlingand additional equipment.

In accordance with one aspect of the invention, the application ofrotating circular knife slitters is extended, so that it is possible toslit a wide web of coiled material into narrow strips having scrollededges. The slitters have suitably shaped cutting edges, the geometry ofwhich constitutes a novel improvement over the prior art. Normally,there would be two counterrotating intergeared cutter shafts, eachcompletely symmetric and, hence, fully balanced for pure rotary motion.Such an arrangement is capable of performing at tangential velocities inthe region of 500 meters per minute without any constraints.

A slitting line constructed in accordance with another aspect of thepresent invention could, for instance, consist of an uncoiler, a rotaryslitter and a recoiling arrangement suitable for several narrow coils.Because of high speed capability, simplicity of operation and a lessexpensive slitting arrangement, the cost of such a longitudinalscrolling operation should be comparable to that of a standard slittingoperation. In addition to providing strips having single, double, tripleand even quadruple rows of blanks, depending on the ultimate conversionarrangement, blanks may be punched on a simple press. Normally, suchmaterial would be blanked leaving afterwards a skeleton shred, whichneeds to be chopped for easier handling. The width of the shred willvary depending on material thickness and cut edge diameter, so theultimate material area utilization factor will depend on the width ofthe shred.

The present invention creates the opportunity to dispose of the shredaltogether, thus increasing the area of material available forprocessing, which not only improves the economics of the process, butalso decreases the material handling problems due to the absence ofshred. Such material saving is accomplished, in accordance with afurther aspect of. the invention, by suitable slitting which leads tothe formation of twelve-sided blanks. This is accomplished by employingan additional operation which involves the removal of triangular-shapedfragments from the scrolled edges. There are several ways of removingthe triangular-shaped fragments. Firstly, the scrolled web can be fedstraight into the cupping tool, which is provided with additionalcropping facilities creating, however, handling problems for thetriangles. Secondly, the triangles could be punched out before theslitting operation. Thirdly, the triangles could be removed after theslitting operation. Following the second and third triangle removingmethods, the web may be fed to the cupping tool, which would be providedwith a simple cropping tool to isolate one twelve-sided blank from thefront or leading end of the web. In such a case, the die and the blankholder of the cupping tool have to be suitably shaped to clamp theentire area of the twelve-sided blank.

The provision of twelve-sided blanks creates an opportunity tocompensate for the effect of anisotropy of the material. For example, inthe case of ferrous materials, the steel makers arrange the stripfinishing operation in such a way that normally after cupping a circularblank, a cup with six ears is obtained. Two ears are directly in linewith the direction of rolling, whereas the other four ears are displaced60° from the direction of rolling. Between the ears the cup is shorterand in effect six valleys are formed. The wall thickness at the ears islower and at the valleys material thickening takes place, which iscaused by the fact that the cup is shorter in these localities, and alsoby tangential shift of material from the ears to the valleys.

With twelve-sided blanks, it is possible to add some material at thelocalities where valleys are expected between the ears. By coincidence,ears are positioned at the points of tangency with other blanks in the60° staggered blank pattern, and the valleys are opposite the unutilizedarea of material, which is normally lost with the shred skeleton. Hence,in practice, there is an opportunity not only to compensate for theeffect of earing but to permit the use of even more material, bydecreasing the area of the triangles, to create ears at the localitiesof valleys, which then in turn displaces some material tangentially intothe original ears, thus resulting in a higher cup compared with the cupmade from a circular blank. It is therefore possible to decrease thediameter of the blank by 1-2%, the exact amount being determinable byexperimentation. It is thus evident that the twelve-sided blank offersmaterial savings thanks to three parameters: (a) the absence of shredbetween tangential circle pattern, (b) the possibility to compensate forthe effect of earing and (c) the opportunity of utilizing a limitedfurther amount of material from a normally unused area in the skeleton.

The benefits of the twelve-sided blank are great and the presentinvention, in accordance with another aspect of the invention,contemplates the conversion of wide coiled webs and sheets intotwelve-sided blanks or into cups from twelve-sided blanks by applicationof a suitably tooled single action press or by application of adouble-action cupper. Obviously, such a system is especially adapted forhigh volume production, or for a high speed twelve-sided blankpreparation, or for slow speed or low output two-piece can making. Therewould be depending on the blank size, five or more blanking toolspreceded by the same number of triangular punch sets, each set havingtwo punches per corresponding blanking tool. The edges of the wide webhave to be prepared suitably by cutting off the web width allowance andremoving large triangular segments between two blanks and the edge ofthe web. Hence, the superfluous material from the web is removed beforereaching the blanking tool, which is deemed, advantageous, since blankscan be then taken away at the back of the blanking press without anyhindrance normally created by the scrap disposal arrangement.

According to a still further aspect of the invention, it is possible tocombine scroll slitting with cutting up of the webs into short lengthstrips or sheet. Essentially, it is necessary to punch out thetriangular holes before presenting the web to the slitting andcutting-up equipment, thereby enabling the scroll slitting cutters toperform their function without any interference from the crop-off dies.The triangular hole punching assembly includes two counterrotating,backlash-free intergeared shafts, the top shaft carrying punches atpredetermined localities and the lower shaft carrying the correspondingdies. The dies are provided with knock-out pads which eject the cut-outtriangles of material into a chute positioned below the lower shaft. Thepre-punched web enters into the scroll slitting assembly, which consistsof two counterrotating blacklash-free intergeared shafts, each beingprovided with ring-type cutters fixed rigidly on the shafts. The sidefaces of these cutters are suitably shaped to slit the web passingtherebetween along lines inclined at 30° to the direction of the webmovement. At the localities corresponding to the triangular holes, thereare positioned straight cropping dies with their edges in line with theaxis of the cutter shafts. The cropping dies may be positioned at theintervals corresponding to the pitch of the triangular holes in the web,and, in such a case, twelve-sided blanks would be produced directly fromthe web. It is, of course, possible to install one cropping tool only toproduce double-scrolled strips, which may be used subsequently for roundhole blanking and cupping, or these strips may be cut up into twelvesided blanks in a separate arrangement, or on the conversion machinewhich draws cups from the twelve-sided blanks during the firstoperation. This aspect of the invention simplifies the scroll slittingline, since it disposes of the recoiling system and of narrow webhandling provisions. Instead blank stacking facilities are required. Theblank stacking nd storing system must be compatible with the feedingarrangement on the conversion machine.

The application of longitudinal scroll slitting techniques to theproduction of twelve-sided blanks is made possible by the adaptation ofthe well-proven slitting arrangement, for straight sided webs, toinclude scrolled features, which embrace cutting lines inclined to thedirection of web movement at any angle between 0° and 90°. Thiscapability is made possible by special novel features in the apparatus,which define exactly the relationship between the two counterrotatingand backlash-free intergeared cutter shafts and the strictly definedrelationship between the cutting edges, to maintain and ensure correctcutting clearance, which is ideally one-tenth of the material thicknessvarying normally for can stock between 0.15 mm and 0.20 mm, without anyclash between the cutting edges. Having determined the requirements inthe geometry of the cutting edges, it is not only possible to slit alongstraight lines, but also to extend the slitting principles to angularslitting and to cutting across the movement of the web, while stillmaintaining a correct cutting relationship between the tool edges,thereby enabling punching of round holes and triangular holes with toolsperforming simple rotating motions, characteristic of the familiarslitting arrangement, which as will be shown, lends itself for "flyingshear" operations well known in the coiled material cutting-upprocesses. By the nature of the arrangement for slitting in which allworking parts perform constant speed rotary motion, there is littlelimitation to the output rate. Controlling the blanks after slitting andcropping might be more difficult because of the multi-lane character.

In summary, the present invention converts coiled material into blanksfor two-piece can manufacture, while maximizing material utilization.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, reference is madeto the following detailed description of various aspects of theinvention considered in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a plan view of a wide web, straight slit, or wide sheet, slitwith single row narrow webs or strips according to known art andpractice;

FIG. 2 is a plan view of a wide web, straight slit, or wide sheets, slitinto double row narrow webs or strips according to known art andpractice;

FIG. 3A is a plan view of a wide web or sheets, fully staggered,suitable for multi-die blanking or cupping as used generally for D&I(Draw and Iron) and DRD (Draw-Redraw) cupping and which is also knownart and practice;

FIG. 3B is a plan view of a wide sheet primarily and secondarilyscrolled to provide single row staggered strips in accordance with knownart and practice;

FIG. 4A is a side view of apparatus for effecting a so-called "primaryscrolling" of webs into sheets in accordance with known art andpractice;

FIG. 4B is a top view of the apparatus illustrated in FIG. 4A;

FIG. 4C is a schematic illustration of the subsequent positions of thescrolled sheets and strips during their passage through a secondaryscroll shearing line arranged in accordance with known art and practice;

FIG. 5A is a plan view of a wide web longitudinally scroll slit by amethod and an apparatus according to one aspect of the presentinvention;

FIG. 5B shows the dimensional relationship of the scroll geometryaccording to a slight modification of the aspect of the invention shownin FIG. 5A;

FIG. 5C shows a typical can end component;

FIG. 5D shows a double row longitudinally scrolled web;

FIG. 6A is a plan view of a wide web longitudinally scroll slit combinedwith punched triangular holes according to another aspect of theinvention to produce twelve-sided blanks;

FIG. 6B is a plan view of a fragment of the web showing the dimensionalrelationship of the scroll geometry of a twelve-sided blank withtriangular shaped material segments still attached thereto;

FIG. 6C is a cross-section of a typical easy open end component forbeverage cans;

FIG. 6D shows, diagrammatically, a progression of operations to producethe end component of FIG. 6C;

FIG. 6E shows a fragment of a scrolled web;

FIG. 6F shows a drawing and wall ironing tool for the conversion ofdodecagon blanks into can bodies;

FIGS. 7A-7F show the effect of material anisotropy on the height of thecup drawn particularly from ferrous materials using circular andnoncircular blanks;

FIG. 8A is a plan view of a twelve-sided blank pattern selected tocompensate for the effect of anisotropy of material according to afurther aspect of the invention;

FIG. 8B is a plan view on an enlarged fragment of the layout of FIG. 8Ashowing the dimensional relationship of the scroll geometry in detail;

FIG. 9 is a layout view of a wide web according to yet another aspect ofthe invention, whereby triangular-shaped holes are punched in the webprior to cupping followed by a cupping from twelve-sided blanks in amulti-die tool actuated by a reciprocating press;

FIG. 10A is a plan view of a wide web according to a still furtheraspect of the invention, whereby longitudinal scroll slitting iscombined with a cutting up across the web to produce double scrolledsheets, strips or twelve-sided blanks;

FIG. 10B is a diagram of a perforated and side-trimmed section of a webaccording to another aspect of the invention;

FIG. 10C shows a dodecagon blank adapted to be converted into a"twist-off cap";

FIG. 10D shows the "twist-off cap" produced by means of the bland shownin FIG. 10C;

FIGS. 11A, 11B and 11C show the tool geometry for effectingstraight-line slitting using two counterrotating cutter shafts in an endview, side view and top view, respectively;

FIG. 12 is an enlarged view of a new and improved tool geometry forcutting a web by flying knives attached to two counterrotating,backlash-free intergeared shafts;

FIGS. 13A, 13B and 13C are diagrams of scroll slitting cuttersconstructed in accordance with the invention;

FIG. 13D shows the assembly for the scroll slitter incorporating thebasic slitting tool components illustrated in FIGS. 13A, 13B and 13C;

FIGS. 14A and 14B are diagrams showing triangular hole punching toolsand alternative round hole punching tools, respectively;

FIG. 15A is an end view of a pair of mating punching tools in a punchingassembly;

FIG. 15B is a side view of the tools illustrated in FIG. 15A;

FIG. 15C shows a slitting assembly adapted to separate the pre-punchedwide web, as illustrated in FIG. 10A, into narrow single blank row webs;

FIGS. 16A and 16B show the application of the rotary slitter to a flyingshear for effecting primary scrolling;

FIG. 16C shows the principal layout of a combination of rotary edgetrimming and rotary shearing according to a further aspect of theinvention;

FIG. 17 illustrates a slitting line arrangement constructed inaccordance with the aspect of the invention shown FIG. 5A;

FIG. 18 illustrates a slitting line arrangement constructed inaccordance with the aspects of the invention illustrated in FIGS. 6A and8A;

FIG. 19 illustrates a slitting and cutting up line arrangementconstructed in accordance with the aspect of the invention illustratedin FIG. 10A; and

FIG. 20 is a graph showing the comparison of material utilizationfactors for round blanks and twelve-sided blanks.

DETAILED DESCRIPTION

FIG. 1 shows a prior art layout of a wide web or sheet 1, which has beenslit into strips 1a to produce straight line edges 1b. The web 1 has awidth "W" and is made up of "M" number of strips plus a web widthallowance factor "d" on both edges thereof. More specifically, the widthdimension of each strip is equal to the sum of the blank diameter "D" ofeach blank 1c and twice the width of a strip shred "a", or M=D+2a. Thus,the width "W" of the web 1 is equal the number of strips "M" plus theweb width allowance factor "d" on each side thereof or W=M (D+2a)+2d.

If this web 1 is cut up into sheets along lines 2 transverse of thelongitudinal axis of the web, then normally the sheet length "L" can becalculated as follows:

    L=N D+(N-1)b+2c+2e,

where

N=number of blanks 1c in the length L;

b=longitudinal distance between the cut edges of each blank 1c;

c=distance between the first and last cut edge and the transverse cutline 2 of the strip 1a; and

2e=longitudinal trim allowance.

The material utilization factor "U" in this case is low and governed bya formula: ##EQU1##

If, for example, D=200 mm, M=4, N=5, a=1.5 mm, b=1.5 mm, c=1 mm, e=1.5mm, and d=1.5 mm, then L=1011 mm, W=815 mm and the material utilizationfactor U is 76.26%.

When the web 1 is slit into four narrow strips 1a, then the materialutilization factor will increase to U=76.52%.

FIG. 2 illustrates a further prior art sheet layout with two strips 1d,each with a double row of blanks 1c. In this case, the sheet length "L"will be the same as in FIG. 1 but the sheet width "W" will be less sincethe dimension "a" does not appear between the blanks, namely:

    L=N·D+(N-1) b+2c×2e=1011 mm

    W=M(D+a+b/2)+2d=812 mm

Thus, the material utilization factor for this sheet is U=76.54% and forthe strips 1d U=76.80%.

The improvement in the material utilization factor is marginal comparedwith single blank row strips 1a of FIG. 1, but even this marginalimprovement is worthwhile.

FIG. 3A illustrates a further and worthwhile prior art arrangement andis regarded as a competitive layout consisting of a fully staggeredsheet or web layout. Due to the fully staggered arrangement of theblanks 1c, the distance "Z" between the centers of adjacent staggeredarranged blanks 1c, lying each in adjacent blank rows, is ##EQU2## andtherefore the distance Y between adjacent row center lines ##EQU3## Ifthe web is primarily scrolled as by represented by nonstraighttransverse scroll lines 3, then its sheet length is as follows.

    L=ND+(N-1) b+2c

The coil web and sheet width dimensions are identical, namely:

    W=(M-1)√3(d+b)/2+2a+2d+D

If, for example, N=5, M=4, D=200 mm, a=1.5 mm, b=1.5 mm and c=1 mm, thenL=1008 mm and W=729.5 mm.

In this embodiment, the material utilization factor for the primaryscroll is U=85.45%.

In the case of coiled material, the utilization factor increases toU=85.49%, which is a minimal increase, but the primary scroll operationis omitted. Coil is used for all D&I (Draw and Iron) operations, whereasthe primarily scroll sheets are essential for DRD (Draw-Redraw) canmaking, which requires surface coating by using sheet coating equipmentalready in existence and widely used by can makers.

FIG. 3B illustrates a further prior art sheet layout for primarilyscrolled and secondarily scrolled sheet to produce single row strips.This sheet layout shows the transverse nonstraight scroll lines 3according to the embodiment of FIG. 3A and is further provided withlongitudinal nonstraight scroll lines 4, which form the lateral edges ofeach single row strip. The material having this geometry could beapplicable for low output can making.

In this case, the sheet length is as follows:

    L=ND+(N-1) b+2c

The sheet width can be computed as follows:

    W=(M-1) X+D+2a+2d

where ##EQU4## which is the distance between the center lines ofadjacent strips of blanks.

If for example, D=200 mm, M=4, N=5, a=1.5 mm, b=1.5 mm, c=2 mm, d=1.5 mmand X=176.23 mm, then L=1008 mm and the coil width W=734.69 mm. Thus,the material utilization factor is U=84.84%.

Compared with the previous case (FIG. 3A) of a primarily scrolled sheet,the material utilization factor has dropped by 0.61%, but still may beconsidered acceptable.

FIGS. 4A, 4B and 4C show the equipment for so-called "primary scrolling"of webs and "secondary scrolling" of sheets to achieve the mostefficient material utilization according to present practice, when theultimate product requires a protective coating, or the conversionequipment is capable of accepting either coated primarily scrolledsheets of single, double or multiple row, secondarily scrolled strips orsheets.

Obviously, the overall economics of the process is influenced not onlyby the percentage of material utilization, but by capital cost contentof the material preparation equipment, cost of running such equipmentand the inevitable scrap handling, however small it may be due toadditional operations. Hence, the cost of the equipment and process ofthe existing operations must be compared with those according to theinvention in order to establish the feasibility and justification forthe longitudinal scrolling operation.

FIGS. 4A and 4B illustrate a coil cutup assembly. The coil is placed onan "up-ender", which changes the attitude of its center line from thevertical to the horizontal orientation and at the same time placing itin a "V" holder of a rotary coil car, which delivers the coil to anexpandable mandrel of an uncoiler adapted to correctly uncoil eitherfrom the top or from underneath. From the uncoiler, the web of thematerial passes between two guide rolls into a visual inspection areaconsisting of two mirrors set at suitable angles to permit viewing ofboth sides of the web at the same time. The web enters a "rollerleveler" (or flattener) which is set up to remove any permanentcurvature from the web. From the leveler, the material drops into a loopat a constant linear velocity. A sensing device keeps the mean depth ofthe loop, from which the material is taken upwards intermittently into aweb feeder, and meters precise lengths of the web passing between twoscroll dies. The material stops when the dies close. When the dies open,a sheet is taken away by an extract conveyor, while the metering rollsof the feeder feed or advance a precise length of the web between thedies of the scroll shear.

Individual sheets are then conveyed into sheet stacking devices of aclassifier, which normally is provided with four stacker boxes. Thefirst two stacker boxes accept sheets with "surface defects" and "offgauge", whereas the third and fourth boxes accept, in turn, the primequality sheets.

The prime quality sheets are normally provided with suitable surfacecoating before conversion into products. In the case of high outputconversion equipment, whole sheets are fed into multi-die presses. Inthe case of low output conversion equipment with single tools, theprimarily scrolled sheets have to be secondarily scrolled to single rowstrips as shown in FIG. 3B. To do that, a special secondary scrollinginstallation is needed, as diagrammatically illustrated in FIG. 4C. Asecondary scroll line consists of a destacker, which advances singlesheets onto a sheet feeder table, whereby they are moved stepwise bysuitable feed bars towards scroll dies operated by a reciprocatingpress. When single row strips are scrolled, a side movement is needed onthe feed table, which results in zig-zag movement of sheetscharacterized by one pitch forward movement and a half pitch sidemovement, to correctly present the primarily scrolled sheets preciselyto the secondary scroll dies. When a scrolled strip is sheared away, itis placed on a stack by an automatic strip take-off mechanism operatingbetween the scroll shear and the stacker. FIG. 4C does not show themechanisms involved in the individual machines, but it indicates thesubsequent positions of the scrolled sheets and strips during theirpassage through the secondary scroll shearing line.

To realize savings, both primary and secondary scrolling equipment maybe avoided. This is being done overwhelmingly in case of a Drawing andWall Ironing (D & I) process, which accepts uncoated stock. Obviously,coated coiled material may be fed directly into the conversion equipmentif production volume justifies coil coating installations.

For low volume production, where single tool equipment is adequate, asingle row scrolled coil would be ideal and could be already applicablefor "Mini D+I" installations, whereby no coating is needed. Scrolledsingle row coils could be produced by modifying the "Edge Trimmer" inthe coil preparation line, and also by adapting the recoilingprovisions. However, this is one of a number of possibilities. Mostprobably, a dedicated longitudinal scrolling line may prove mosteconomical, because of high speed potential.

Availability of longitudinally scrolled coils may lead to narrow coilcoating developments, thus widening the scope of the present invention.With this in mind, what follows is a discussion of various aspects ofthe present invention.

FIGS. 5A and 5B illustrate a web layout for a scroll slitting operationcarried out in accordance with one aspect of the present invention andutilizing an apparatus constructed in accordance with another aspect ofthe invention. An identical longitudinal scroll shape is repeated fourtimes in pairs. The geometry is similar to that in FIG. 3B. However, theillustration in FIG. 5A shows how the pattern of the layout has beengradually changed from the illustration on FIG. 3B by taking intoconsideration a longitudinal scroll line 4a, which, in this embodiment,is tangent to a generating circle of "G" diameter. It can be seen that:

    G=D+2b

whereby "D" is the blank diameter and "b" is the shred width allowance.It is also evident from FIG. 5A that the scrolled blank row width "V_(a)" is:

    V.sub.a =D+2a

where "a" is the narrow web width allowance which normally is alwaysgreater than the shred width allowance "b". An increase in the dimension"a" is permissible without any detriment to the material utilizationfactor, since in the middle of the coil the dimension "V_(a) " isindependent of the shred dimension "b", and on the extremes at the wideweb edges the negative influence is minimal since its increaseddimension normally takes some material from the web width allowancedimension "d".

Longitudinally scrolled webs have a slightly improved materialutilization factor, which in the embodiment of FIG. 5A is: ##EQU5##assuming that D=200 mm, M=4, N=1, L=201.5 mm, W=734.69 mm. The materialutilization factor U therefore is slightly better than in the layout ofFIG. 3B.

Although the illustration shows narrow webs having single blank rows,double or multiple blank rows could be obtained by the same method, andthe webs thus obtained would be suitable for blanking, leaving a shred.

In the more detailed fragmentary illustration of FIG. 5B, thenonstraight longitudinal scroll lines 4a have scroll line sectionsparallel to the longitudinal axis of the blank rows and at a distance"f" parallel to the tangent of the generating circle of "G" diameter.Suitable values for the distance "f" can be selected according topractical requirements. An example for an assumed value of the distance"f" will be given in context with the description of a furtherembodiment illustrated in FIGS. 8A and 8B.

As shown in FIG. 5B, the width "V_(b) " of a scrolled blank row iscalculated as follows:

    V.sub.b =D+2b+2f.

The length "2(L)" of the scroll line sections parallel to thelongitudinal axis of the blank rows can be calculated with the help ofthe geometrical relations given in FIG. 5B. An exemplary calculation isalso specified in connection with FIGS. 8A and 8B.

FIG. 5C shows a typical can end component 110 stamped from thismaterial. In this case it is of circular shape surrounded by a seamingpanel 111, which in the can closing operation interlocks with the canbody component. The center of the end component is normally depressedand suitably shaped, and referred to as countersink panel 112. Accordingto present practice, the end component 110 is made in one operationusing a suitable combination tool, which first blanks a circular discand then draws the seaming panel 111 and forms the countersink panel112, the starting material being single row or double row scrolledstrips obtained by a system shown in FIG. 4C producing the stripsillustrated in FIG. 3B.

FIG. 5D shows a double row longitudinally scrolled web 113 made from awide web material similar to that illustrated in FIG. 5A, except thatthe web of FIG. 5A has been slit into single row webs. The double rowweb 113 can be fed into a standard double die end stamping press, whichwould normally accept double scrolled strips from a stack magazine, orfrom a coil placed on a simple uncoiling arrangement in a form of arotating table placed on the floor, such set-up being well known foruncoiling wire and narrow webs from large coils. In order to transportthe longitudinally scrolled web through the end stamping press, theexisting feed bar arrangement can be modified for the feed fingers toengage in the scrolled shape. Alternatively a new feeding arrangementcould be devised as well as a skeleton cutting guillotine.

Application of the longitudinally scrolled webs in end making offerssubstantial labor savings. The new can end making equipment may becheaper and more efficient as any risk of stoppages caused by scrolledstrip handling have been avoided.

FIG. 6A illustrates the layout of a wide web, whereby the longitudinalscroll slitting along scroll slitting lines 4b follows a triangular holepunching operation which punches out equilateral triangles 6 in order toprovide twelve-sided blanks 5. It can be seen that the sides of theblanks are tangent to the generating circle of "G" diameter, which inthis embodiment coincides with the calculated blank diameter "D". Hence,in effect, there is no shred which results in a material savingsreflected in a narrower coil required for the same cut edge diameter asfor the example of FIG. 3B.

Web width therefore is W=(M-1)√3D/2+D+2d.

If, for example, D=200 mm, M=4 and d=1.5 mm, the coil width W equals722.62 mm.

The material utilization improves because of the narrower coil. That is,##EQU6##

Over 2.8% material gain has been achieved by employing the method andthe slitting apparatus according to this aspect of the invention.

As shown in detail in FIG. 6B, the material punched out (hatchedtriangles or V-shaped notches 6) of the material of the web is shaped inan equilateral triangle form and has side lengths "g" equal to D.tan15°=0.267949D and the dimension "K" across the peaks of the symmetricaltwelve-sided blanks is 1.035276D, it being understood that such anincrease over the value "D" should not cause problems during theconversion of the blanks to cups.

FIG. 6C shows a cross-section of a typical easy open end component 114for beverage cans, which is characterized by a so called "key hole"score line 115 and a tab 116 attached to a centrally located rivet 117.Such an end component is normally made in a number of operations,starting with end shell making in a standard end making press, and thenconverting the shell to include the easy opening features in a separatepress complex which also makes the tabs before attaching them onto theends.

FIG. 6D shows diagrammatically a progression of operations necessary toproduce easy open ends from longitudinally scrolled webs according tothe invention, as illustrated in FIG. 6A.

In this case, the web is fed from a coil into a simplified conversionpress, which retains the standard tool making facility, but the endshell handling arrangement is replaced by the scrolled web itself. Theconversion operations into easy open features are performed on the webitself. Finally, when the tab is attached, the shell is made in a lastoperation as shown in FIG. 6C.

Benefits arising from the system as shown in FIG. 6D are obvious. Onemay save equipment for end shell making and a great deal of handlingarrangements for end shells prior to conversion into easy open ends.Furthermore, the conversion equipment employing the scrolled web may berun at higher speeds.

FIG. 6E shows a fragment of the scrolled web according to the inventionas illustrated in FIG. 6A. In this case, by suitable cropping of the webalong a shortest possible cross line 119, equilateral dodecagon blankscan be obtained. These dodecagon blanks are then converted into canbodies in a drawing and wall ironing tool as shown in FIG. 6F.

With reference to FIGS. 6E and 6F, the web is fed into the drawing toolhaving a punch 121 and a blankholder 118 provided with a cropping edgeon one side, which cooperates with the corresponding cropping edgeattached to a draw die 120. After detaching one blank from the web, theblank is clamped between the blankholder 118 and the draw die 120. Thisis followed by a punch 121 contacting the blank and drawing it throughthe draw die 120 to produce a cup. Subsequent travel through threeironing rings 122, 123, 124 of decreasing internal diameters reduce thecup wall thickness, thus increasing its height.

Due to the dodecagon shape, the edge of the wall ironed can has aregular saw tooth-like shape. The can stripping device may be modifiedsuitably to cater for this shape.

Application of the dodecagon blanks in wall ironing might be foundeconomically attractive by avoiding the shred in the material skeleton,thus gaining savings.

FIGS. 7A-7F illustrate the effect of the material anisotropy on theheight of the cup drawn from ferrous materials using circular andnoncircular blanks.

In FIG. 7A, a plan view of a circular blank 5 is shown in relation tothe rolling or grain direction and also in relation to other blanks,assuming the most economic layout of a 60° pattern. The diagramindicates the positions of potential ears which normally occur on a linecoinciding with the direction of rolling and at positions of 60° fromthe directions of rolling. Between the ears there are positions ofvalleys shown at 30°, 90°, 150°, 210° and 330°. A second smallerconcentric circle on FIGS. 7A denotes the cup F of a diameter equal toabout 60% of the blank diameter. This means that 20% of the blankdiameter, is making up the cup height, which, assuming the retention ofconstant material thickness after cupping, should be ideally 27% ofblank diameter made from totally isotropic material.

FIG. 7B illustrates an elevation of the cup in which "H" denotes theideal cup height. The actual cup edge is far from a straight line inthis view. To illustrate the effect of anisotropy, the development ofthe cup wall is shown in FIG. 7C, which indicates clearly the positionsof the ears, at 0°, 60°, 120°, 180°, 240° and at 300°, at which pointsthe cup height is greater than the ideal height "H". At locationsbetween the ears, the cup height is lower than the ideal height "H" byan amount depending on the degree of anisotropy.

As shown in FIG. 7A, the ears are located at positions where thegenerating circles are tangent, or at positions of least shred betweenthe cut edges. The valleys, on the other hand, are adjacent to thetriangular areas, which are normally scrapped as part of the shredskeleton. This observation points towards the proposal that noncircularblanks might be beneficial in increasing material utilization.Experiments confirmed that about 2.5% difference in blank diameter atpositions of valleys to compensate for the effect of earing, producedcups of more even height. However, taking advantage of this observationmight not be practicable in producing blanks for subsequent use, but itcould be applicable when cupping is executed from the web. In FIG. 7A,the idea of compensation for earing has been indicated by dotted lines.The benefit is obvious, as it might offer a material saving of an orderof 2.5% compared with a circular blank.

FIGS. 7D, 7E and 7F illustrate how twelve-sided or dodecagon blanks canbe modified to compensate for earing, the main advantage being theelimination of shred between the blanks to thereby save about 1% of thematerial, compared with circular blanks. The left-hand side of FIGS. 7D,7E and 7F shows the effect of an equilateral dodecagon on the cupheight, which manifests itself in twelve sharp peaks around the edge ofthe cup. The cup height in the valleys between the peaks would be equalto "H" which is the height characteristic of ideal isotropic material.The influence of anisotropy manifests itself in deeper valleys atpositions of 30°, 90°, 150°, etc. below the line of ideal height "H",whereas at positions 0°, 60°, 120°, etc. corresponding to ear positionsthe valleys' depth decreases well above the "H" line. There is a directcomparison here with circular blank with superimposed effect of peakscaused by the dodecagon shape.

The right-hand side of FIGS. 7D, 7E and 7F shows the effect ofcorrection of the blank shape to eradicate the effect of anisotropy. Atthe positions of the valleys, the sides of the dodecagon are not tangentany more to the generating circle of "D" diameter. These particularsides become therefore shorter, and the sides opposite the potentialears become longer. It is possible to balance the lengths of themodified dodecagon sides in such a way that the cup height over alltwelve valleys in the cup edge will be equal. This new height will begreater than the ideal "H" characteristic for isotropic material, and ofcourse similar to that of the corrected circular blank of "D" diametergenerating circle.

The benefits of the modified dodecagon are obvious, primarily due to thepossibility of utilizing the scrap material in the shred skeleton.

In the extreme case, the dodecagon becomes a hexagon, which uses up allthe triangular area between blanks. Unfortunately, the side trim of theweb increases and any potential economic advantage offered by hexagonalblanks would be lost.

FIG. 8A shows how the effect of anisotropy may be compensated for andhow more material area may be made available for cupping. Thetwelve-sided blank layout in a 60° configuration ideally satisfies theconditions according to this aspect of the invention. More particularly,the effect of anisotropy may be compensated for by making the triangularpunched holes 6a smaller than calculated in FIGS. 6A and 6B in which thetwelve-sided blank 5 is equilateral. Once the triangular holes 6a aremade smaller, then the blank ceases to be equilateral. It is a simpleroutine calculation to determine the decreased size of the triangularhole. This will depend entirely on the difference: Q-D; Q being theincreased dimension of the blank at the localities where valleys 8 areexpected between the ears 7.

In FIG. 8B, the dimensional relationship between the blanks 5, thelongitudinal scroll lines 4d to be slit and the triangular holes 6a tobe punched out are shown in more detail than in FIG. 8A.

As an example of illustration in FIGS. 8A and 8B, it is assumed that Qis 2.5% greater than D. This means Q=1.025D. Therefore, with the help ofthe formula f_(a) =1/2 (Q-D), the allowance f_(a) (as shown in FIG. 8B)can be calculated as follows: f_(a) =0.0125D.

Because the length ga of the full side of the 60° triangle, which isgreater than the one to be punched out is

    g.sub.a =(2-√3)D=0.2679492D,

the decreased side L_(a) of the triangle 6a can be expressed as follows:

    L.sub.a =g.sub.a -2 f.sub.a .√3=0.2246D

Further, the increased side dimension h_(a) taken from the obliquedsection of the scroll line 4d which is tangent to the blank diameter Dcan be calculated:

    h.sub.a +g.sub.a +2 f.sub.a .√3-g.sub.a (2-√3)/2.

It can be shown that when Q=D, then L_(a) becomes the length of the sideof a twelve-sided polygon, i.e., 0.267949D, which is also ga, the sidelength of the equilateral triangle. In an extreme case, the whole areaof this triangle is available for the blank area, and the blank becomesa hexagon, the side of which is 0.57735D.

The area of the twelve-sided polygon is as follows:

    A.sub.12 =0.267949D·D/4 ·12=0.803847D.sup.2

which is smaller than that of a hexagon, namely,

    A.sub.6 =0.57735D·D/4·6=0.866025D.sup.2

and both are higher than an area of a circle

    A.sub.circle =0.785398D.sup.2

The ratio of dodecagon area to the area of a circle is 1.02349, which is2.3% greater. The area gained by compensating for earing can beexpressed as follows:

    A.sub.X =L.sub.a (0.07735D=0.0125D)=0.0030789D.sup.2 per one triangle.

Hence, the total area is six times greater.

    A.sub.X6 =0.01847D.sup.2

Hence, the increased area of the dodecagon can be expressed as follows:

    A.sub.dodeca =0.803847D.sup.2 +0.01847D.sup.2 =0.822317D.sup.2

The ratio of increased dodecagon area to the area of the circle is##EQU7##

The ratio of an increased dodecagon to an equal sided one is ##EQU8##

(These calculated values arise also from the assumption that "Q"=1.025D,leading to the allowance of f_(a) =0.0125D.

Such a combination appears to increase the material available forforming the container by 2.3%, which would mean that for a givencontainer the blank area could be 2.3% smaller.

FIG. 9 shows how the concept of a twelve-sided blank can be extended tostandard cupping operations.

The blank holder shape has to be modified to suit the polygonal shape,and likewise the blanking or cropping dies. The cupping tools must bepreceded by a double row of triangular hole punching tools. Likewise webedges have to be trimmed and triangles of material between two blankshave to be cropped away. It can be seen from FIG. 9 that the leadingblanks 5A on the web 1 need to be cropped along one side t₁ of the blankpolygon, whereas the second row of blanks 5b is cut a maximum of fivetimes t₅ and a minimum of three times t₃ depending on whether the blank5b is in the middle of the web 1 or at its edge.

The punching and cropping assembly, which is only schematicallyindicated in FIG. 9, serves to punch out the triangular materialsections 6c between the blank rows and to crop the outer edge shred 9 ofthe wide web 1. Both the triangular sections 6c and the outer edge shred9 are marked as hatched sections in FIG. 9.

Present practice standard cupper tools are followed by a shred cuttingguillotine, which is attached to a die bolster (not shown). In thearrangement according to this aspect of the invention, the punching andcropping assembly may be attached to the front of the die bolsters,without any need for an additional actuating mechanism. This also meansthat a scrap conveyor can be placed in front of the press, and thereforethe back of the press is kept free for the conveying of cups, which isan additional advantage.

FIG. 10A illustrates a web layout according to another aspect of theinvention. FIG. 10A has some similarities with FIG. 6A. Basically, inthe direction of feed of the web 1, there is first provided a punchshaft assembly to blank-out triangular holes 6d in the side strips ofthe blank rows. The size of these triangular holes will depend on thedecision whether to compensate for the anisotropy of the material (asdescribed on the basis of FIG. 6B), and it will be less than the maximumcharacteristic dimension of the twelve-sided polygon of g_(a) =0.268D,whereby g_(a) is the length of the sides of the triangle. The length ofthe side of an equilateral triangle could well be reduced to half lengthof the equilateral dodecagon. The thus-perforated web 1 proceeds theninto a slitting and cropping assembly, which compared with that in FIG.6A (longitudinal scroll slitting only), has an additional capability ofcutting across the scroll-sided web to produce either multiblank strips"L_(m) " containing a small number of blanks 5c, most probably greaterthan 2, or individual twelve-sided blanks 5 d. Hence the slitting diesof the slitting and cropping assembly will cut along lines "s", thelengths of which will be greater than g_(a) =0.268D, and the respectivecropping dies will cut along lines "t", which will be greater than g_(a)=0.268D, depending on the degrees of compensation for anisotropy.

The punch shaft assembly also removes fragments 10 of the material fromthe edges of the web 1. This enables the slitting assembly to removeunwanted offcuts 11 from the edges of the web, thus offering completeuniformity of narrow webs, strips or blanks, not depending on whetherthey are taken from the middle or the edges of the wide web 1.

It will be seen that there are a number of benefits arising from thepresence of triangular holes in the coil prior to slitting along linesinclined at an angle of between 0° and 90° to the direction of webtravel. These benefits are primarily associated with tool making. Also,the presence of the triangular holes 6d enables cutting across, orcropping off a length of web, to produce strips and/or blanks withgreater ease. The triangular holes also serve the purpose of aligningthe coil precisely in relation to the slitting and cropping dies, sincethe ability to cut and slit with precision is the basis for this aspectof the invention.

FIG. 10B shows a diagram of the perforated and side-trimmed section of aweb 1 according to yet another aspect of the invention. The illustrationaims to explain that the dodecagon basic grid can be applied to a webfrom which four rows of twelve-sided blanks 5e are to be separated alongdiscrete lines, after removing triangles of material 6e and trimming theedges as scrap 11a.

It is anticipated that the savings in coating of the coil and due to arecycling of uncoated scrap will offset the overall cost of the productarising from the conversion of the coil.

Obviously, the application of the perforating technique is feasible onlyfor high outputs wherein a perforating unit can be inserted in the coilpreparation line. This unit could replace the present edge trimmer.

FIG. 10C shows a dodecagon blank made by a method illustrated in FIG.10A, this blank being subsequently converted into a "twist-off cap", asection of which is shown in FIG. 10D. A significant benefit in thiscase is manifested by a possibility of using the additional materialfrom the corners of the dodecagon blank to form the lugs. Cut-edgesavings might be achieved by decreasing the curl size opposite the flatsof the blank. Of course, the number of lugs can be increased dependingon the size of the cap.

FIGS. 11A-11C show an arrangement 20 for slitting wide webs 1 intonarrow webs. In FIGS. 11A-11C, the arrangement 20 is shown in differentviews. FIG. 11A illustrates a cross-sectional view in the direction ofthe rotational axes of two superposed cylindrical shafts, that is, anupper shaft 21 and a lower shaft 22. FIG. 11B is a side view and FIG.11C is a top plan view of the shaft arrangement. At both ends, thesuperposed shafts 21 and 22 are supported by bearings 23 whichrotationally mount these shafts in a machine frame 23A. As shown inFIGS. 11B and 11C, the shafts 21 and 22 are coupled together by twomeshing gears 24, which counterrotate along with the shafts.

Each shaft 21, 22 carries cutter dies 25, 26 mounted on its cylindricalsurface by various fasteners. The fasteners ensure that the cutting sidefaces 25a, 26a of the respective cutter dies 25, 26 are in preciseperpendicular relationship to the rotational axes of the shafts. This ismost important in order to maintain the slitting clearance necessary forburr-free edges on the narrow webs. The cutter dies 25, 26 are arrangedin pairs as shown to avoid axial thrust on the bearings 23. The physicalrelationship between the shafts 21, 22 has to be ensured by preloadedbearings, as axial shaft movement cannot be tolerated since the idealcutting/slitting clearance between the cutters is one-tenth of thematerial thickness "t_(m) ", which could be as low as 0.015 mm. Hence,the cutting clearance would be 0.015 mm, meaning that the differencebetween the cutter cutting faces on opposite shafts is Wu-W1=0.03 mm.The amount of cutter cylindrical surface overlap would be at least onematerial thickness "t_(m) ". The effect of the amount of cutter overlapcan be seen in the web/strip deflection after slitting up or down,depending on the actual position.

Positive advancement of the web 1 through the slitter arrangement 20 is,ensured by so-called draw rolls 27 positioned between the cutter dies25, 26. These draw rolls grip the coil by friction and push it throughthe slitting knives of the cutter dies.

The basic slitter arrangement 20, as seen, is simple and its "modusoperandi" is limited primarily to a rotary motion to perform theslitting operation on the laterally guided web. One object of thisaspect of the invention is to perform a more complicated slittingoperation on the same simple arrangement consisting of the twocounterrotating shafts 21, 22 provided with suitable tooling 25, 26, 27capable of producing a longitudinal scroll shape slitting effect. Hence,the geometry of scroll slitting tools and the ability to make thesetools are two important aspects of this invention.

FIG. 12 illustrates the technique for cutting the web perpendicularlyand across 90° to its direction of movement (see the layout of FIG. 10A)using a rotary slitter mechanism provided with flying (or rotary) dies.It can be seen that flying cutter action across the traveling web may becombined with the rotary slitting action along the traveling web toresult in a scroll-slitting action at any angle. In FIG. 12, the uppercutting edge 25a is rotating around the center "O_(U) " and the loweredge 26a turns about the center "O_(L) " at the same angular velocities.This means that the pitch cylinders of both shafts are contacting androlling without any slip, since the respective pitch circle radii "R_(U)" and "R_(L) " are equal. To achieve the correct cutting relationship ofthe cutting edges, the lower tool 26 in FIG. 12, which is leading, hasto have an addendum "ad" above the pitch circle, which may be equal toabout two material thicknesses "t_(m) ", whereas the trailing edge has adedendum "dd", which results in a lower linear velocity of the uppercutting edge relative to the lower cutting edge. The dedendum may beequal to material thickness "t_(m) ", thus the maximum engagement ofboth cutting edges "n" would be equal to the material thickness "t_(m)".

As seen in FIG. 12, the cutting clearance between the upper and lowercutting edges 25a and 26a, respectively, is negative before the contactwith the material as shown at points "G" and "H". At point "J" when bothcutting edges, after penetrating through the material thickness "t_(m)", have met, the cutting clearance might be zero, but in practice itwill be minimal, about one-tenth of the material thickness "t_(m) ".From point "J" onwards, the clearance between the cutting edges isincreasing steadily as shown at points "P" and "S". This means that nointerference may take place between the cutting edges, particularly whenthey move out of engagement.

There is a relationship between the pitch circle radii "R_(U) " andR_(L) ", tool engagement "n", angle of tool engagement "2α" and the toolclearance, when moving out of engagement. An approximate value of theangle can be calculated from the cosine formula: ##EQU9##

Given the angle α, the tool clearance "cl" equals:

    cl=6 n sin. α=2 (ad+dd) sin. α

The tool engagement "n" has to be checked also from the deflectionaspects of both cutter shafts. Both addendum "ad" and dedendum "dd" mayhave to be increased, so under the load conditions the tool engagement"n" is at least between one-half and one material thickness.

FIGS. 13A-13C illustrate a rotary cutting and shearing technique for thepurpose of longitudinal scrolling as shown diagrammatically in FIG. 5A,whereby a wide web 1 is divided into four narrow webs with scrollededges 4a. It shows how it is possible to combine the well-knownlongitudinal slitter, normally used for straight-linear slitting as inFIG. 1, with cutting across the coil, by modifying the slitting cuttersto the shape as in the arrangement 32 shown in FIGS. 13A-13C.

FIG. 13A shows the application of rotary cross-cutting to longitudinalscroll slitting, whereby the slitting line assumes inclined paths inrelation to the slitting direction at about 30°. This means that alongthese lines there is a condition in which cross-cutting is combined withslitting. In case of cross-cutting, identical rules must prevail asshown in FIG. 12, in which the leading cutting edge must be above thepitch circle defined by radius "RL", while the trailing cutting edgemust be inside the pitch circle defined by radius "RU".

In FIG. 13A, it is shown clearly how the leading inclined cutting edgeAL-BL interacts with the trailing edge AU-BU. The points AU-BU generatecontracted epicycloids in relation to points AL and BL. Theseepicycloids are therefore the respective "Loci" of points AU and BU.Between points BL and CL interaction takes place with line BU and CU,resulting in standard slitting action. However, these lines have tocross the pitch circles in order to create the correct conditions forcombined cross-cutting and slitting along C-D lines, whereby the topedge CU-DU assumes the leading position and the bottom edge CL-DL istrailing. In this case the bottom points CL and DL generate contractedepicyloids in relation to CU and DU.

In FIG. 13C, only two pairs of cutters 25d, 26d are shown. These cuttersare identical and are provided with suitably shaped side faces 28a, 29awhich correspond to the required scroll shape. On the right in FIG. 13C,the cutters 26d are positioned back-to-back with a spacer 30 in between.On the left, the cutters 25d are oriented on the shaft 21 front-to-frontwith a spacer 31 in between. The distance or thickness of the spacer 31is such that the scrolled web width "V_(a) " (FIG. 5A) is obtained. Thecutters are, of course, rigidly attached to the shafts by well-knownmeans (not shown) to ensure not only their axial positions on theshafts, but also their angular positions, both being vitally importantfor correct functioning of the arrangement 32.

In FIG. 13B, the front faces 28a, 29a of the cutters 25d and 26drespectively, are illustrated. In this case, there are eight basicscroll shapes. For simplicity in the manufacture of the dies, thevalleys 33 are of constant width and depth, and can be made by means ofparallel profile grinding. In between the valleys 33, tapered shapes ortops 34 are formed. These tops 34 can be surface ground to ensurecorrect height in relation to the depth of the valleys 33.

Obviously, the cutter shafts 21, 22 have to be intergeared (i.e., gears24 in FIG. 11B) without any backlash to maintain a correct tangentialrelationship. The shafts 21, 22 are provided with suitable thrustbearings (i.e., bearings 23 in FIGS. 11B and 11C), whereby correctpre-loading will ensure the necessary axial relationship to maintain thedesired axial cutting clearances.

To ensure the positive advancement of the web 1 through the scrollslitter, draw rolls 35 (FIG. 13C) might be provided, which then grip theweb by friction against the cutter cylinders 25d and 26d, respectively,thus ensuring correct profiles of the scrolled webs.

FIG. 13D shows the assembly of the scroll slitter incorporating thebasic slitting tool components illustrated in detail in FIG. 13C. Inorder to slit a wide web into five narrow scrolled webs, shaft 21carries three sets of cutters 25d, and shaft 22 correspondingly bearsthree sets of cutters 26d. Draw rolls 35 are provided between individualcutter sets 25d and 26d to grip the web against opposite cuttersurfaces. Both shafts 21 and 22 are rotatably mounted in pre-loadedbearings 23 located in bearing blocks 23a. Gears 24, which are of thebacklash-free type, ensure a synchronized relationship between bothshafts 21 and 22.

FIGS. 14A and 14B are a side view and a plan view, respectively, showinghow the technique illustrated in FIG. 12 can be used for the purpose ofpunching holes in a web, using two counterrotating intergeared slittershafts. In FIG. 14A, a tool 36 for punching a triangular hole is shownschematically. Here again the principle of the trailing edge movingslower than the leading edge has been maintained and the levels of boththe punch and the die faces 37 and 38, respectively, have to changeaccordingly depending on the geometry of the hole. In the case of atriangular hole, one has to compromise in one sharp corner, so the toolface level can be changed from leading to trailing and vice versa.Punching a circular hole as seen in both views in FIG. 14B requires amuch simpler tool 39. Both tool faces 40 and 41 of this tool 39 areinclined to correspond to a leading and trailing configuration.

FIG. 15B shows the schematic principle of the punching assembly whichcooperates with the slitting assembly illustrated in FIG. 18. Basicallythere are two counterrotating intergeared shafts as in any slittingmachine. The top shaft 101 is provided with punches 102 of triangularshape and the lower shaft 103 is tooled-up with dies, which cooperatewith the punches. The tool geometry is shown in FIG. 15A. To obtain thenecessary precise notching of tool components in both slitter shafts,there are two types of rings fitted on the cutter shafts. One form ofrings consists of just plain rings provided with cutting edges on bothsides. Another form of rings includes "V" notches, which in the top toolprovide the precise guidance for the punches, and in the bottom toolthey serve as cutting dies, the edges of which cooperate with the edgesof the punches.

By the punching tool action, the triangular fragments of plate arepushed into the die. These fragments have to be pushed out by a positiveknock-out 104 operated by an eccentric shaft 105 mounted inside thelower slitter shaft 103. This eccentric shaft is constrained andprevented from rotating.

FIG. 15C shows the slitting assembly which separates the pre-punchedwide web, as illustrated in FIG. 10A, into narrow single blank row websrepresenting a row of dodecagon blanks by cutting the web along lines S(see FIG. 10A) inclined to the direction of web feed at 30°. In order toslit precisely along the lines S in relation to the punched triangularholes, locating pegs 102c are fitted in the external pairs of slittercutters 26s. The locating pegs 102c engage the triangular holes in theweb by wrapping the web around the peg-carrying slitter shaft prior toslitting. The internal slitter cutter assemblies 26d-s and 25d-s aremerely slitting the web, whereas the exact synchronicity with thepunched holes is achieved by the pegs fitted in the outer scroll cutterassemblies.

FIGS. 16A and 16B illustrate a technique for cutting up the web 1 intoso-called primary scrolled sheets along nonstraight transverse scrolllines 3 as illustrated in FIG. 3A. In this case, rotary slitting iscombined with cropping across the web by means of flying or rotary dies.Indeed the invention in this embodiment is of an extreme character.Nevertheless, the basic mechanism is similar to the typical slittingarrangement with two counterrotating intergeared shafts. A top punchshaft 40 carries a punch 41, which is trailing, hence its diameter isDs=L7/π less dedendum; while a bottom die shaft 42 carries a leading die43 which has its diameter increased by an "addendum". Both shafts 40 and42 are intergeared by a pair of backlash-free gears 44 (FIG. 16B). Sincethe circumference of both punch and die shafts 40 and 42 is equal to thesheet length L (FIG. 3A), cutting of the web takes place at a constantweb and mechanism velocity. To ensure the required sheet lengthaccuracy, the coil 1 passes between two feed rolls, namely, a top feedroll 45 and a bottom feed roll 46, which precede the punch and dieshafts 41, 42. Both feed rolls 45, 46 have identical diameters "Df" andare intergeared by gears 47 (FIG. 16B), so their surfaces 48, whilecontacting the web 1, are moving at the same velocity. FIG. 16Aillustrates that the top feed roll 45 is driven by the die shaft 42through a feed drive gear 49, the ratio of which is Ds:Df. Since "Df" issmaller than "Ds", the feed rolls 45, 46 are rotating faster than punchand die shafts 40, 42, but the tangential velocities are identical. Todirect the web in a precise lateral relationship to the die 43, the web1 passes from a loop (not shown) over a web deflector roll 50, which isprovided with guide flanges 51, which contact the edges of the web overa certain wrap angle. Normally there will be additional edge guides (notshown) on both sides of the feed rolls 45, 46. To ensure a positive gripon the web passing between the feed rolls 45, 46, the bottom feed roll46 can move up and down by pneumatic means (not shown), which isstandard practice in similar applications.

The deep scroll punch and die 41 and 43 are made precisely in a similarway as those normally used in a reciprocating application, i.e., theprofiled faces are perpendicular to the base surface. However, the topsurface 52 is ground to a cylindrical shape. Slight corrections to theprofile of the die and punch must be introduced to compensate for punchdedendum and die addendum.

FIG. 16c shows schematically how the present invention, according to anadditional aspect, could be adapted, using the combination of a rotaryedge trimmer shaft assembly and a rotary flying shear shaft assembly,for use in conjunction with a rotary slitter principle. The end product,which is a single row multi-blank strip 55, is well known in presentconversion practice, whereby a crank-operated reciprocating press cutsup the web along a scroll line. The apparatus, basically aimed atlongitudinal scrolling, may be modified to perform the web cutting-upoperation at an angle which, in the illustrated case, is close to 30°.In this case, there could be a cosine of 30° relationship between theweb width "W" and strip length "L". The material usage efficiency Uwould be similar to that achieved by the technique illustrated in FIG.4. However, similar and easier strips are obtainable by a combinationshown in FIGS. 10A and 10B.

FIG. 17 shows schematically one embodiment of a scroll slitting lineconstructed in accordance with the present invention to produce narrowlongitudinally scrolled webs from a wide web, as shown in FIGS. 5A and5B. More particularly, a coil C of wide material is placed on anexpanding mandrel 56 of an uncoiler 57 and is positively clamped frominside, so that it can be rotated in a controlled manner. The web 1 ofthe material taken from the coil C passes over a rotatably mounteddancer roll 58 mounted on a pivot arm 59. The arm 59 of the dancer roll58 operates a switch 60, which controls the revolutions of the uncoiler57 to maintain a constant tension on the web. The web 1 of the materialthen passes over a deflection roll 50a, controlling its lateral positionand bringing it onto the feeding and processing plane. A pair of feedrolls 45a, 46a intergeared with a slitting assembly 61 (see FIGS. 16Aand 16B) meters the web at a precise rate into the slitting cutter ofthis assembly, which divides the wide web 1 into a narrow web alongscroll lines 4b and 4c similar to those illustrated in FIGS. 5A and 5B,respectively. By the nature of the arrangement of the slitting assembly61, some narrow webs 1a will be deflected upwardly and some downwardlydepending on the combination of the associated slitting cutters. Thenarrow webs 1apass afterwards over individual adjustable deflector rolls62 before being recoiled on a recoiler 63.

Although only one recoiler is shown in FIG. 17, in practice there willbe at least two. This is necessary due to a scrolled edge character.Most probably, individual coils will have side plates to facilitaterecoiling in the first place, and then to protect the scroll edges fromhandling damage. FIG. 17 does not show the disposal means for the edgetrim.

In this arrangement of the simple slitting assembly 61, it is importantto maintain a "no slip" condition between the feed rolls, so thescrolled profiles are accurate, which is absolutely essential forsubsequent processing of the scrolled webs.

FIG. 18 illustrates schematically another embodiment of a scrollslitting line constructed in accordance with the present invention. Inthis embodiment, an additional operation is contemplated prior to thelongitudinal slitting. This operation involves the punching oftriangular boles in the web in a precise pattern, which is compatiblewith the scroll slitting geometry.

As in the previous embodiment shown in FIG. 17, there are uncoiling andrecoiling provisions 57a and 63a which could be similar and theirfunctions would be identical.

The major difference manifests itself in the work station consisting ofa punching assembly 64 and a slitting assembly 61a, both beingintergeared by a blacklash-free gear arrangement 65. To achievesynchronization betweeen the punching assembly and the slittingassembly, there has to be a micro-adjustment (not shown) between thedriving gear of the punch assembly 64 and the hub of the driven shaft.This is absolutely essential, as the punched holes 6, 6a in the web 1must synchronize with the locating pegs on the shafts of the slittingassembly 61a. The locating pegs (not shown) ensure that the angularslitting takes place in exact and precise relationship to the triangularholes, thus avoiding and preventing formation of slivers which would bedetrimental on a number of accounts, but above all the consequentialinaccuracies would make the scrolled web useless for further processing.After slitting, the narrow webs 1aremain in contact with th.e respectiveshafts over a certain wrap angle (shown are different sized wrap anglesat the respective slitting shafts), ensuring that at any time two pairsof locating pegs are engaging in V notches provided in the slit webs.These V notches are previously created in the punching assembly.

The arrangement as described above is capable of producinglongitudinally scrolled webs which may be cut up eventually toequilateral dodecagon blanks. It is also possible to arrange the toolsin such a way that compensation for anisotropy (FIGS. 6B, 8A) might beintroduced, which results in modified dodecagons after the cutting up ofwebs into individual blanks. Basically the principle of generating the"grid" for blanks is similar, but the triangular holes 6a are smaller ifcompensation for anisotropy is contemplated.

FIG. 19 illustrates schematically a further embodiment of a scrollslitting line constructed in accordance with the present invention inwhich the web 1 is subjected at first to a triangular punchingoperation, which is subsequently followed by slitting along angled slitlines combined with cropping across the slit web (FIG. 10A). In thisembodiment, the triangular punched holes (6d in FIG. 10A) must becompatible with the scroll slitting and lateral cropping tool geometry.

As in the previous two embodiments, the uncoiling provisions 57b areidentical. Also, the punching assembly 64a is similar to that in FIG. 18and is driven from a slitting and cropping assembly 66 through anintergear 65a. In between the work assemblies, a deflector roll 67,which is freely rotating, lifts the coil upwards, primarily to create awrap angle around the top shafts of both assemblies to ensure precisesynchronization. It follows that when punching dies of the punchingassembly 64a are in progressive engagement, at least two pairs ofpunches locate the web on the top punching shaft 68 due to the wrapangle indicated, thus ensuring the highest degree of precision in thelongitudinal positions of the triangular holes (6d in FIG. 10A).

The slitting and cropping assembly 66 must be capable of producingindividual dodecagon blanks (5d in FIG. 10A), hence cropping dies arefixed in suitable localities in between locating pegs (not shown)engaging in V notches provided in the punched web. The wrap angle aroundthe top shaft 68a of the slitting and cropping assembly 66 ensures notonly correct synchronization for longitudinal slitting, but also for thelateral cropping of the narrow webs. Here again at least two pairs ofthe locating pegs (not shown) have to engage the web prior to slittingat the instant when cropping takes place (see FIG. 10A left position).This constraint defines the magnitude of the wrap angle.

After slitting and cropping, multi-blank strips (5c in FIG. 10A) orindividual dodecagon blanks (5d in FIG. 10A) are deposited on suitableconveyors 69 for final delivery into stacker boxes 70. Obviously, twostacker boxes preceded by two conveyor assemblies are necessary forefficient stacking.

FIG. 20 is a graphical representation of the material utilization factorU as a function of the number of rows N in the web for (1) round blankswith a one percent of diameter shred, (2) twelve-sided blanks withoutany shred and (3) twelve-sided blanks with compensation for earing.

The trend is evident. Narrow webs having less than three rows of blanksare simply uneconomical.

The difference between no shred and a 1% shred is 1.75% in materialutilization, which is substantial. This means that twelve-sided blankscan be justified economically and can be used to also compensate for theeffect of earing by offering up to 2.5% more material for conversioncompared with the equilateral twelve-sided blanks. Compared withpresently established practice, area utilization is improved by about4.25% which is substantial.

Obviously, the saving of material depends on the degree of earing, whichis influenced by the material properties arising from composition,rolling degree, and the heat treatment.

The position of points on the graphs showing the material utilizationfactor can be determined by mathematical formula as follows: ##EQU10##where

a=shred allowance

D=blank diameter

N=number of rows

The formula is valid for positive and zero values of shred allowance"a".

The same formula appears to be valid if additional material is takenfrom the shred and added to the blank, as takes place when compensatingfor "earing". In such a case, "a" has a negative value.

It has been shown by calculation that for a 2.5% gain in the materialutilization factor, the allowance "a" should be "-0.0141D".

The formula for the graph showing compensation for earing is as follows:##EQU11##

The intermediate values up to N=8 have been entered in the graph.However, since the material utilization factor is not influenced bygeometry alone, but also by material anisotropy, the values for thematerial utilization factor must be deemed as "estimated".

Nevertheless, the modified dodecagon blanks improve materialutilization, in addition to achieving the "zero" shred advantage derivedby employing an equilateral dodecagon.

It will be understood that the embodiments described herein are merelyexemplary and that a person skilled in the art may make many variationsand modifications without departing from the spirit and scope of theinvention. All such variations and modifications are intended to beincluded within the scope of the invention as defined in the appendedclaims.

We claim:
 1. Apparatus for dividing a web of metallic material into aplurality of strips from which polygonally-shaped blanks are to be made,comprising perforating means for perforating said web at predeterminedlocations, said perforating means including a first set of cutting toolsmounted for rotation in one arcuate direction and a second set ofcutting tools mounted for rotation in an opposite arcuate direction suchthat each cutting tool of said first set cooperates with a correspondingone of said cutting tools of said second set to perforate said web assaid web is fed between said first and second sets of cutting tools;longitudinal scroll slitting means for slitting said web along at leastone scroll line which extends generally longitudinally along said web,said longitudinal scroll slitting means including a third set of cuttingtools mounted for rotation in one arcuate direction and a fourth set ofcutting tools mounted for rotation in an opposite arcuate direction suchthat each cutting tool of said third set cooperates with a correspondingone of said cutting tools of said fourth set to slit said web along saidat least one scroll line as said web is fed between said third andfourth sets of cutting tools; and deflecting means positioned betweensaid perforating means and said longitudinal scroll slitting means fordeflecting said web such that said web is partially wrapped about saidcutting tools of one of said first and second sets of cutting tools andsaid cutting tools of one of said third and fourth sets of cuttingtools.
 2. The apparatus of claim 1, further comprising lateral crossslitting means for slitting said web along a plurality of separatinglines, each of said separating lines extending generally transversely ofsaid web.
 3. The apparatus of claim 2, wherein said lateral crossslitting means cuts said web into a plurality of individual strips. 4.The apparatus of claim 3, further comprising transporting means fortransporting said individual strips to stacking means for stacking saidindividual strips one on top of the other.
 5. The apparatus of claim 3,wherein a plurality of blanks can be made from each of said strips,whereby each of said strips can be cut into a plurality of blanks. 6.The apparatus of claim 3, whereby only a single blank can be made fromeach of said strips, whereby each of said strips is a blank.
 7. Theapparatus of claim 2, wherein said lateral cross slitting means includesat least a pair of cooperating cutting tools having cutting edges whichtravel at the same angular velocity, said cutting edges having asubstantially zero clearance between them at a point before they reachtheir maximum engagement.
 8. The apparatus of claim 1, wherein saidfirst set of cutting tools is mounted on a first rotatable shaft andsaid second set of cutting tools is mounted on a second rotatable shaft,said first and second shafts being mounted generally parallel to eachother and being driven in synchronization with each other throughanti-backlash gearing.
 9. The apparatus of claim 8, wherein said firstset of cutting tools includes punches and said second set of cuttingtools includes dies which cooperate with said punches to punch outpolygonally-shaped pieces of material from said web as said first andsecond sets of cutting tools are rotated conjointly with said first andsecond shafts, respectively.
 10. The apparatus of claim 9, wherein saidpunches and said dies have a triangular cross-sectional shape and haveinclined faces, one of which trails the other.
 11. The apparatus claim9, wherein said perforating means perforates said web before said web isslit along said at least one scroll line by said longitudinal scrollslitting means.
 12. The apparatus of claim 11, wherein said third set ofcutting tools is mounted on a third rotatable shaft and said fourth setof cutting tools is mounted on a fourth rotatable shaft, said third andfourth shafts being mounted generally parallel to each other and beingdriven in synchronization with each other through anti-backlash gearing.13. The apparatus of claim 12, wherein said third and fourth sets ofcutting tools include cutting edges having profiles which correspond tothe shape of said scroll lines, the cutting edges of said third setleading the cutting edges of said fourth set.
 14. The apparatus of claim13, wherein said leading cutting edges extend beyond a pitch circle oftheir corresponding cutting tools of said third set and said trailingcutting edges do not extend to a pitch circle of their correspondingcutting tools of said fourth set, whereby said trailing cutting edgeshave a lower linear velocity then said leading cutting edges.
 15. Theapparatus of claim 14, further comprising feeding means for feeding saidweb between said third and fourth sets of cutting tools.
 16. Theapparatus of claim 15, wherein said feeding means includes draw rollsmounted on said third and fourth shafts.
 17. The apparatus of claim 16,wherein said first, second, third and fourth shafts are driven insynchronization with each other through anti-backlash gearing.
 18. Theapparatus of claim 1, wherein said deflecting means includes a deflectorroll which is movable transversely of said web.
 19. Apparatus fordividing a web of metallic material into a plurality of strips fromwhich polygonally-shaped blanks are to be made, comprising perforatingmeans for perforating said web at predetermined locations, saidperforating means including a first set of cutting tools, includingpunches, mounted on a first rotatable shaft for rotation in one arcuatedirection and a second set of cutting tools, including dies, mounted ona second rotatable shaft for rotation in an opposite arcuate direction,said first and second shafts being mounted generally parallel to eachother and being driven in synchronization with each other throughanti-backlash gearing such that each punch of said first set of cuttingtools cooperates with a corresponding die of said second set of cuttingtools to punch out polygonally shaped pieces of material from said webas said web is fed between said first and second sets of cutting toolsand as said first and second sets of cutting tools are rotatedconjointly with said first and second shafts, respectively, andlongitudinal scroll slitting means for slitting said web along at leastone scroll line which extends generally longitudinally along said web,said longitudinal scroll slitting means slitting said web along said atleast one scroll line after said perforating means perforates said weband said longitudinal scroll slitting means including a third set ofcutting tools mounted on a third rotatable shaft for rotation in onearcuate direction and a fourth set of cutting tools mounted on a fourthrotatable shaft for rotation in an opposite arcuate direction, saidthird and fourth shafts being mounted generally parallel to each otherand being driven in synchronization with each other throughanti-backlash gearing such that each cutting tool of said third set ofcutting tools cooperates with a corresponding one of said cutting toolsof said fourth set of cutting tools to slit said web along said at leastone scroll line as said web is fed between said third and fourth sets ofcutting tools, said third and fourth sets of cutting tools includingcutting edges having profiles which correspond to the shape of said atleast one scroll line, said cutting edges of said third set of cuttingtools leading said cutting edges of said fourth set of cutting tools andextending beyond a pitch circle of their corresponding cutting tools ofsaid third set of cutting tools and said cutting edges of said fourthset of cutting tools extending short of a pitch circle of theircorresponding cutting tools of said fourth set of cutting tools, wherebysaid cutting edges of said fourth set of cutting tools have a lowerlinear velocity than said cutting edges of said third set of cuttingtools.
 20. The apparatus of claim 19, further comprising lateral crossslitting means for slitting said web along a plurality of separatinglines, each of said separating lines extending generally transversely ofsaid web.
 21. The apparatus of claim 20, wherein said lateral crossslitting means cuts said web into a plurality of individual strips. 22.The apparatus of claim 21, wherein a plurality of blanks can be madefrom each of said strips, whereby each of said strips can be cut intoplurality of blanks.
 23. The apparatus of claim 21, wherein only asingle blank can be made from each of said strips, whereby each of saidstrips is a blank.
 24. The apparatus of claim 21, further comprisingtransporting means for transporting said individual strips to stackingmeans for stacking said individual strips one on top of the other. 25.The apparatus of claim 20, wherein said lateral cross slitting meansincludes at least a pair of cooperating cutting tools having cuttingedges which travel at the same angular velocity, said cutting edges ofsaid at least a pair of cooperating cutting tools having a substantiallyzero clearance between them at a point before they reach their maximumengagement.
 26. The apparatus of claim 19, wherein said punches and saiddies have a triangular cross-sectional shape and have inclined bases,one of which trails the other.
 27. The apparatus of claim 19, furthercomprising feeding means for feeding said web between said third andfourth sets of cutting tools.
 28. The apparatus of claim 27, whereinsaid feeding means includes draw rolls mounted on said third and fourthshafts.
 29. The apparatus of claim 28, wherein said first, second,third, and fourth shafts are driven in synchronization with each otherthrough anti-backlash gearing.
 30. The apparatus of claim 19, furthercomprising deflecting means positioned between said perforating meansand said longitudinal scroll slitting means for deflecting said web suchthat said web is partially wrapped about said cutting tools of one ofsaid first and second sets of cutting tools and said cutting tools ofone of said third and fourth sets of cutting tools.
 31. The apparatus ofclaim 30, wherein said deflecting means includes a deflector roll whichis movable transversely of said web.